As complete host resistance in soybean has not been achieved, Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum continues to be of major economic concern for farmers. Thus, chemical control remains a prevalent disease management strategy. Pesticide evaluations were conducted in Illinois, Iowa, Michigan, Minnesota, New Jersey, and Wisconsin from 2009 to 2016, for a total of 25 site-years (n = 2,057 plot-level data points). These studies were used in network meta-analyses to evaluate the impact of 10 popular pesticide active ingredients, and seven common application timings on SSR control and yield benefit, compared with not treating with a pesticide. Boscalid and picoxystrobin frequently offered the best reductions in disease severity and best yield benefit (P < 0.0001). Pesticide applications (one- or two-spray programs) made during the bloom period provided significant reductions in disease severity index (DIX) (P < 0.0001) and led to significant yield benefits (P = 0.0009). Data from these studies were also used in nonlinear regression analyses to determine the effect of DIX on soybean yield. A three-parameter logistic model was found to best describe soybean yield loss (pseudo-R2 = 0.309). In modern soybean cultivars, yield loss due to SSR does not occur until 20 to 25% DIX, and considerable yield loss (_697 kg ha_1 or _10 bu acre_1) is observed at 68% DIX. Further analyses identified several pesticides and programs that resulted in greater than 60% probability for return on investment under high disease levels.
Bibliographical noteFunding Information:
Funding: Financial support was provided by the Illinois Soybean Association, Iowa Soybean Association, Michigan Soybean Promotion Committee, Wisconsin Soybean Marketing Board, Minnesota Soybean Research and Promotion Council, and North Central Soybean Research Program for their generous support of this research. For Michigan studies, additional funding was provided in part by DuPont Crop Protection and the USDA-ARS Specific Cooperative Agreement number 58-5442-4-017 (National Sclerotinia Initiative).
- Baseline sensitivity
- Brown rot
- Genetic diversity
- Monilia mumecola